1. Field of the Invention
The present invention relates to a flexible printed circuit and a display module comprising the flexible printed circuit; more specifically, relates to a flexible printed circuit for electrically connecting the display panel of a display module to a printed circuit board.
2. Descriptions of the Related Art
With the ever increasing use of consumer electronic products, high performance and light weight are required of modern electronic products. In corresponding to this trend, flexible printed circuit (FPC) boards with flexible characteristics have been widely used in various electronic equipments, such as various kinds of displays, laptops, mobile phones, digital cameras, personal digital assistants (PDA), printers and optical disc drives.
As shown in FIG. 1, a general flexible printed circuit structure comprises a flexible substrate 10 and a cover lay 11, wherein the flexible substrate 10 comprises an upper surface and the cover lay 11 is disposed on the upper surface of the flexible substrate 10. Two opposite sides 12, 13 of the cover lay 11 are continuous linear contours that extend along the lengthwise direction of the flexible substrate 10. While the flexible printed circuit is subjected to external forces (especially pulling, dragging, or twisting during assembling, transporting, and repairing) or is influenced by thermal expansion and compression that may generate unpredictable deformation, the produced stresses (tension or torsion stress) would be transferred to any frequently stressed surface of a printed circuit layout 14. Consequently, this may result in a development of a fracture or breakage condition in any region of the flexible printed circuit, further causing system malfunction. Because the breakdown region on the printed circuit is too small to be identified by eyes, it is difficult for maintenance workers or users to inspect such failures, hindering the overall repairing process.
As shown in FIG. 2, to solve the aforesaid problem concerning structural failure of the flexible printed circuit, existing techniques fabricate two sides 21, 22 of the cover lay 20 as a continuous extending wavy contour. Although the continuous extending wavy contour can buffer or scatter the concentrated stress of the printed circuit layout 24 to resist the fracture of leads, two end portions 25, 26 may still be susceptible to possible fractures due to an increased number of external dragging and pulling. The reason is that the problem of concentrated stress of the two end portions 25, 26 is not solved effectively. Because at least one of the two free end portions 25, 26 is usually the region of a lead for providing power to the whole system, a fracture in this area would cause the most serious damage.
Consequently, increasing the fracture resistance for the whole structure of the flexible printed circuit (especially for the two end portions of long printed circuits) without increasing fabricating difficulties is an objective for the corresponding industries.